The invention relates to a method of repairing surface defects in image or picture films. More specifically, the invention relates to filling in depressions such as scratches in the surface of such films.
In connection with the copying of picture films it has been known for a long time that the copying or printing results may be improved by wetting the developed picture film to be copied. In one known method, the picture gate or window and its immediate surroundings are filled with liquid so that the picture film, and in the case of contact printing naturally also the raw film to be exposed, are completely surrounded by the liquid, please see (Journal of the SMPTE, Vol. 66 (October 1957) pp. 607-615; Television and Cinema Technique, (Fernseh- & Kino-Technik) Vol. 34 No. 2, (1980), pp. 60-65.
The major drawback of this known method is seen in that the film transports dirt particles and air bubbles into the liquid, especially the perforations move air bubbles into the liquid. Eliminating these problems takes expensive preventative measures and the threading of the picture film and, if applicable, of the raw film into the printing machine is made considerably more difficult. Disturbances are also caused by splices, especially when the picture film has been subjected to several glazing procedures.
In the second known method, the picture film is passed through between two felt pads which are dampened or moistened with the liquid (System Piclear). In practice, it has been shown that in this method of operation the deeper scratches on the film base or support side are not totally filled in, so that the scratches remain visible in the print or copy and that the felt pads must be constantly monitored since dirt particles cling to these felt pads and such dirt particles may in turn lead to scratches on the picture film.
Both known methods have a drawback in common, in that the drying of the picture film before its winding or coiling-up requires a considerable waste of time and money. Hot-air blowers and a considerably extended film run or path between the picture gate or window and the take-up reel or cassette are necessary so that a printer must be specially constructed for use as a so-called wet-copying or printing apparatus, in particular, an available or existing printer must be completely rebuilt for this wet printing purpose. Such a printer is then only suited for wet-copying or printing. Furthermore, the known wet-copying or printing methods cannot be used for dry-spliced picture film. As is known, for splicing picture films, there are the wet-splice method and the dry-splice method, whereby the dry-splice method is the only one suited for specific films, namely, those having a polyester film base. In the known wet-copying methods, the dry-spliced sections are totally or partially dissolved, so that the dry-spliced films cannot be wet-copied or printed. Since a machine suited for the known wet-copying or printing methods is only usable for wet-copying, a separate printer must be available for dry-spliced films.
A further common drawback of both known methods is seen in that the wetting of the film is suited only for a single film-run speed, which is relatively low due to the necessary drying time, which makes a change-over to variable speeds practically impossible.